1. Field of the Invention
The present invention relates to a waterproof slide fastener in which a plurality of synthetic resin made fastener elements are formed by injection molding on both front and rear faces of one edge portion of a waterproof fastener tape including a waterproof layer made of elastomer resin on a belt-like core material formed by weaving or knitting, and an apparatus for manufacturing the same.
2. Description of Related Art
This kind of slide fastener has a waterproofing structure in which with the fastener tape woven or knitted with fibers as a belt-like core material, both front and rear faces of the core material are covered with an elastomer material such as natural rubber or synthetic rubber, and fastener elements of synthetic resin are formed integrally by injection molding along one side edge of this fastener tape such that each of them strides over the front and rear faces. Usually, an element mounting edge portion of the fastener tape includes through holes which are formed at a forming portion of each fastener element, the through holes acting as a passage route of molding resin for each fastener element and connecting integrally upper and lower half portions of the fastener elements formed on the front and rear faces of the fastener tape.
Because in this kind of conventional slide fastener, however, as disclosed in for example, Japanese Utility Model Application Laid-Open NO. 59-41107, upper and lower half portions of fastener elements are formed on front and rear faces of a fastener tape through through holes formed in an element mounting edge portion of the fastener tape. Accordingly, when this fastener tape is attached to a suit for underwater construction or wet suit, water can ooze out from a front side to a rear side of a slide fastener through a boundary face between the fastener tape and the fastener elements and the through holes at a place where there is a large difference in pressure between the front side and rear side of the slide fastener.
Thus, according to, for example, International Application Publication No. WO 02/03825 A1, front and rear faces of a fastener tape are covered with thermoplastic synthetic resin likely to be chemically fused with fastener elements, such as polypropylene, polycarbonate, polyethylene terephthalate, polybutylene, vinyl chloride, polyamide or high density polystyrene, whereby improving an adhesion of boundary between the fastener tape around the through hole and the fastener elements, aiming at holding water tightness at the boundary. Further, according to the International Application Publication No. WO 02/03825 A1, an end portion on opposite side to a coupling head of the fastener element is formed into an inclined face which is inclined downward toward a tape surface and then, upper and lower flange portions formed to oppose upper and lower blade pieces of a slider which engages and disengages element rows when a sliding operation is performed, are inclined such that the upper and lower flanges approach at a same angle as the aforementioned inclined face, so that the sliding operation of the slider can be carried out smoothly.
Furthermore, according to, for example, Japanese Utility Model Application Publication No. 63-30247, the front face and the rear face of a fastener element are connected to each other by a connecting portion which runs through a through hole formed in an element mounting edge portion of the fastener tape so as to intensify a connection strength between the fastener tape and the fastener element. At the same time, adhesive agent layers are formed on both the front and rear faces corresponding to at least near the through hole in the fastener tape, boundary between the fastener tape and the fastener element around the through hole is sealed with these adhesive agent layers aiming at holding water tightness at the boundary.
Any structure disclosed in the aforementioned publications comprises upper and lower half portions molded symmetrically and disposed on front and rear sides such that the element mounting edge portion of the fastener tape is nipped, and includes: a coupling head which has a gap allowing it to nip an exposed end of the fastener tape and extend outward from the mounting edge of the fastener tape; a neck portion and a body portion which nip and are integrated together on the element mounting edge portion of the fastener tape; and thin right and left shoulder portions which nip and are integrated on the element mounting edge portion of the fastener tape and extend in right and left directions from the neck portion. Further, according to the Japanese Utility Model Application Laid-Open NO. 59-41107 and Japanese Utility Model Application Publication No. 63-30247, a ladder-like fin piece, which narrows gradually toward its tip, extends from an end portion on an opposite side to the neck portion of the body portion such that the fin pieces nip and are integrated on both the front and rear faces of the element mounting edge portion. This ladder-like fin piece is disposed at a position opposing the flanges of the slider so as to guide the sliding of the slider through its outer surface not to make a sliding contact with the fastener tape.
In the slide fastener disclosed in the International Application Publication No. WO 02/03825 A1, a sliding contact area of the slider to the fastener element is large. Even if a component of force applied obliquely downward to the fastener element decreases when the slider is slid, in case of an ordinary slider, this only can meet an increase in sliding resistance accompanied by an increase in the sliding area and thus, there is no guarantee that a smooth sliding operation is secured. Further, the fastener element of this Publication does not include any portion for guiding the sliding of upper and lower opposing faces of right and left flange portions formed on upper and lower blade pieces of the slider. Therefore, the upper and lower opposing faces of the flanges may make a sliding contact with the fastener tape, so that the synthetic resin layers on the front and rear faces of the fastener tape may be flawed by rubbing, thereby possibly leading to reduction in waterproof performance.
On the other hand, in the fastener elements disclosed in the aforementioned Japanese Utility Model Application Laid-Open NO. 59-41107 and Japanese Utility Model Application Publication No. 63-30247, a fin piece is disposed on each side of the front and rear faces at an end portion on an opposite side to the coupling head, the fin piece having a guide surface for guiding the sliding of upper and lower flange end faces of the slider through its surface. Thus, there is no fear that the surface of the fastener tape may be flawed by rubbing unlike the International Application Publication No. WO 02/03825 A1. However, the sliding resistance can not be reduced so much because its sliding area is large. In addition, a body portion molding cavity and a fin piece molding cavity are continuous and areas of them are large when molding the fastener elements. Therefore, pressing force on the fastener tape due to the upper and lower half portions of the body portions and fin pieces formed with the same cavities are likely to disperse, so that a fixing force of the fastener element to the fastener tape likely drops.